This invention relates to an apparatus and method for producing a continuous sheet of dough. More particularly, this invention relates to an apparatus and method for producing a continuous sheet of stress free dough of generally uniform height and width from discrete batches of dough.
The current practice for commercially producing sheets of dough by a batch method generally involves measuring the required dry ingredients (i.e., flour, sugar, yeast, etc.) and mixing them with the appropriately measured liquid ingredients (i.e., water, oil, etc.). The resulting dough paste created by mixing these ingredients is then kneaded until the desired dough batch is developed. A gluten network is formed within the dough batch.
The dough batch is typically then transferred to a retention hopper or bin and co-mingled with previously prepared batches of dough. The dough remains in the retention hopper until it is extruded by a combination of peripherally ribbed oppositely rotating discharge rollers which force the dough mass through an extrusion die or restricted opening to form a continuous stream of dough exiting the retention bin. In the course of forcing the dough through the extrusion die, the discharge rollers forcefully pull the dough from the retention hopper and push it through the restricted opening. Once extruded, the stream of dough can be shaped, rolled, or cut to the desired specifications depending upon the ultimate dough product (i.e., croissant, bread loaf, biscuit, pizza dough, etc.).
As the dough is kneaded, the gluten network develops within the dough. The gluten network is a highly elastic and cohesive gel structure which is generally indicative of the quality of the dough. The more developed and undamaged the gluten network remains in the dough, the higher the quality of the resulting dough product. The gluten in the dough is damaged or destroyed as a result of high stresses or shear forces applied to the dough. Therefore, the less stress imparted to the dough or the more "stress free" the dough remains, the higher the quality of the resulting dough product.
In the practice of the above-described commercial process for producing a continuous sheet of dough, the peripherally ribbed discharge rollers which pull the dough from the retention hopper and force it through the extrusion die exert a significant sheer or tearing force upon the dough. These forces greatly damage and destroy the gluten network within the dough. Additionally, the compression forces applied to the dough by the discharge rollers also damage the gluten network. The resulting stream of compressed dough emerging from the retention hopper is difficult to shape and form due to the damaged gluten network.
The damaged dough can be partially restored if passed through a series of rollers and shapers, but this corrective measure is much more timely and costly than if the gluten network had never been damaged in the first place. An additional corrective measure to rehabilitate the damaged gluten common in the industry is to allow the dough to rest for as much as two hours after extrusion from the retention hopper. Once again, this practice serves to only partially regenerate the gluten network and is inherently time consuming and is a further complicating requirement in producing a continuous sheet of quality, stress free dough. The dough, even after rehabilitation, is of a lesser quality and more resistant to shaping than "stress free" dough.
One prior solution for producing a continuous stream of stress free dough is disclosed in U.S. patent application Ser. No. 07/985,551, assigned to the Assignee of this invention. That invention involves continuously mixing the dry and liquid ingredients which are then transferred to a temperature controlled chamber for continuous kneading which generates a continuous stream of dough. The dough stream is discharged from the kneading chamber, without the benefit of rollers or stress inducing extrusion dies, through a discharge conduit of predetermined flow resistance. The resulting stress free continuous dough stream has a well developed and undamaged gluten network. However, the apparatus and method disclosed in that application is directed to a continuous mixer and continuous kneader for forming a continuous dough sheet. There still exists a need for a method and apparatus for producing a continuous sheet of stress free dough for the batch process in which the ingredients are mixed and then kneaded and discrete batches of dough deposited and co-mingled with other batches in the retention hopper. A batch system for producing dough includes a batch mixer in which the dough is mixed and then kneaded. Batch sizes typically vary from as little as 100 pounds to as much as 2,000 pounds per batch.
A method for producing a continuous sheet of dough for the batch process is disclosed in U.S. Pat. No. 4,904,491 in which the dough is severed into portions by horizontal cutter blades positioned at the bottom of a hopper. In this method, the dough is produced in batches which are then deposited into the hopper. The cutter blades section the dough into individual portions which are each then weighed and placed on a conveyor to occupy a space proportional to their weight. The speed of the conveyor is controlled to correspond to the weight of each portion of dough so that each successive portion is positioned on the conveyor to overlap the previous portion, thereby forming a continuous sheet of dough after rolling and shaping. A problem associated with this method is the involved steps of weighing each portion of dough and regulating the conveyor to overlap each portion. These steps complicate the dough sheeting process. Therefore, the cost of such a system to carry out the method disclosed in U.S. Pat. No. 4,904,491 can be a prohibitive factor to using this method.